Re: dlmopen in LD_PRELOAD

[Baojun Wang <wangbj@gmail.com>]

I believe so, was using glibc-2.27 from ubuntu 18.04 LTS.
Would you try with commit df58c5f3f328110c3e64ebbe667764185909d180 (or git
pull)? I made some mistake in some early commit.

Thanks
Baojun

On Fri, Jun 21, 2019 at 7:53 AM Florian Weimer <fweimer@redhat.com> wrote:

> * Baojun Wang:
>
> > Hi Florian,
> >
> > (re-send because previous email failed to send due to attachment)
> >
> > I made a tiny project this issue, it didn't show the same failure,
> however it did segfaults inside the library being `dlmopen`-ed.
> >
> > link: `git clone https://github.com/wangbj/dlns-test.git`
> <https://github.com/wangbj/dlns-test.git>
> > (sorry attachment seems to cause failure to send message)
> >
> > run.c: an launcher to inject DSOs.
> > preload.c: a mini loader using LD_PRELOAD -> dlmopen
> > dlns.c: DSO being `dlmopen`-ed
> > app.c: app being injected with DSOs.
> >
> > running `make test` should reproduce the issue. (need to run `ulimit
> > -c unlimited` to get core dump).
>
> Sorry, for me, it does not.
>
> This is the output I get:
>
> ./run libpreload.so libdlns.so ./app
> open /tmp/dlns-test/libdlns.so
> dlns_init
> [link_map] dso: /tmp/dlns-test/libdlns.so, loaded at: 0x7f0ca0d53000,
> _DYNAMIC: 0x7f0ca0d56de8
> [link_map] dso: /lib64/libdl.so.2, loaded at: 0x7f0ca0d4d000, _DYNAMIC:
> 0x7f0ca0d51d70
> [link_map] dso: /lib64/libpthread.so.0, loaded at: 0x7f0ca0b12000,
> _DYNAMIC: 0x7f0ca0b2dd60
> [link_map] dso: /lib64/libc.so.6, loaded at: 0x7f0ca094c000, _DYNAMIC:
> 0x7f0ca0b0bb60
> [link_map] dso: /lib64/ld-linux-x86-64.so.2, loaded at: (nil), _DYNAMIC:
> (nil)
> #1 local_getpid addr = 0x401610
> #0 local_getpid addr = 0x401610
> #2 local_getpid addr = 0x401610
> #3 local_getpid addr = 0x401610
> #1 local_getpid: 0
> #1 local_getpid: 0
> #1 my own tls: 1234
> #2 local_getpid: 0
> #2 local_getpid: 0
> #3 local_getpid: 0
> #3 local_getpid: 0
> #3 my own tls: 1234
> #2 my own tls: 1234
> #0 local_getpid: 0
> #0 local_getpid: 0
> #0 my own tls: 1234
>
> Has your glibc been built with --enable-bind-now?
>
> Thanks,
> Florian
>